One common question I hear engineers ask about is if it’s better to have Mica/Grease or Sil-Pad products. Obviously, I’m partial to this, but I wanted to give some thoughts I had about Mica/Grease, and why I think it has its place, but why I think in a manufacturing environment it’s better to go with a Sil-Pad.
Problems with Thermal Grease/Mica Combination
Before I start ranting about this, it’s not necessarily the Mica/Grease combo that causes the problem.. But it’s more the grease that causes the issues.
- Thermal Grease is messy. When I was a kid, I was the kid getting the chocolate bar all over everything. Thermal Grease is the same way- except on steroids. THERMAL GREASE GETS EVERYWHERE. IN THE CONTACTS, ON YOUR PANTS, ON THE CEILING SOMEHOW!??! (its really not that bad, but it can be- you need to be careful with it.)
- Thermal Grease can be improperly applied because every operator is different. In a manufacturing environment, it can be unevenly applied. I watched three videos online the other day, about 30 minutes of instruction.. All had different methods of applying thermal compound to a transistor… then I watched more videos of applying thermal grease to a CPU/Heatsink, and that had all different methods. Each of these methods has a different thermal pad performance.
- Thermal Grease dries out, and pumps out overtime. Thermal expansion during the heat up/cool down causes the thermal grease to pump out of the application- in addition to the changing temperature- the grease will also dry out overtime. As you may have guessed, this is not conducive to good thermal performance.
With all that said, my genuine belief is, in the short-term, applied PERFECTLY, the thermal grease and MICA can provide a better result. However, when stacked up against reality, I think Sil-Pad wins everytime. You have to ask yourself, do I have a perfect application method, and is this product designed to work for a few months to a few years? If the answer is no- consider a Sil-Pad because I bet you are going to get better consistently, and better performance.
Here’s the last thing I’m going to say on this subject. I see a lot of blogs, info on the internet saying “oh, I tried a thin thermal pad and Mica/Grease worked better”- do me a favor and try a real thermal pad that you didn’t buy for $0.20 for some website- its likely you are going get better results.